As an exhaust gas analysis system, as disclosed in Patent Literature 1, there has been one using a constant volume sampling apparatus that is configured to sample the total amount of exhaust gas discharged from an internal combustion engine, dilute the totally sampled exhaust gas with diluent gas to produce diluted exhaust gas, and control the flow rate of the diluted exhaust gas to be constant.
Specifically, this system calculates the concentration of a component in the exhaust gas by collecting the diluted exhaust gas into a diluted exhaust gas bag as well as collecting the diluent gas into a diluent gas bag, and subtracting the concentration of the component in the diluent gas in the diluent gas bag from the concentration of the component in the diluted exhaust gas in the diluted exhaust gas bag.
So-called bag measurement adapted to collect diluted exhaust gas and diluent gas into bags as described above is capable of accurately measuring the concentration of a component, but requires many steps before the measurement, such as calibrating an analyzer in order to measure the diluted exhaust gas and the diluent gas, thus taking a long time to obtain a measurement result.
For this reason, when an obtained measurement result is far out of an assumed range and measurement should be repeated, a time required for bag measurement performed by then goes to waste.
In addition, such a problem may occur not only in the case of the bag measurement but also when exhaust gas is introduced to a filter to measure PM or the like contained in the exhaust gas.
Also, one of causes for taking a long time to obtain a measurement result is the presence of a step of temporarily measuring the diluted exhaust gas in the diluted exhaust gas bag before the bag measurement in order to determine a measurement range used to perform the bag measurement for the diluted exhaust gas bag.
In order to omit the step, it is conceivable that a user assumes the concentration of the component in the diluted exhaust gas to set the measurement range of the analyzer in advance. However, in that case, when the concentration of the component in the diluted exhaust gas is different from the assumed one, measurement accuracy may not be ensured.
In such a situation, separately from the above-described bag measurement, the present inventor has focused on a continuous analyzer used to continuously analyze diluted exhaust gas, such as an analyzer used to calculate a fuel consumption in real time, and intensively examined the problem associated with the bag measurement using analysis results by the continuous analyzer.